Weight shift

[Ringer]

Mandrin:

I am curious about this statement:
"The work done by the central torque is acting on the club through both arm segments"

It seems confirmed by simply removing one of the arms that the ball cannot be struck as far.

But here's my question. You say that it's acting through both arm segments. What kind of torque is being created on the shoulders, and what role do they have in the direction of the force?

 

[shootin4par]

how the arms can be used in the pendulum model. can they add more speed then the pivot alone

take a child and put them on a swing set. you are going to swing the child and the child is held in place at 9:00 before you swing the child, they will swing down to 6 and up to 3. While they are going down gravity and torque from the shoulders will propel them. can you assist those two with the arms as well?
3 options,
A. now you could just drop the child, gravity, shoulder turn and add no arm force, they will probably swing just past 3.

B. You cauld have the child drop from 9:00 while you stand by the bottom of the arc and try to apply help from the 7:30 position, the child is going fast by that time and you will be lucky to add 5% to the childs speed, so they will swing up slightly where they swung in option A

option C. You could stand at the top and push them as they dropped and pulled. At this point they are going the slowest and your help, along with gravity and the shoulders can propel them way past 3

throw from the top, the best way to add speed if you know how to do it right?

 

[JeffM]

Shootin4par states with respect to the pendulum model.

option C. You could stand at the top and push them as they drop. At this point they are going the slowest and your help, along with gravity can propel them way past 3.

The presumption of this pendulum model is that there is no central torque generator operant, that operates through movements of the central body. In the modern, total body golf swing, the central torque generator starts the downswing, and it's the true source of power in option C. If the central torque generator is optimally operant, then no additional "arm pushing power" is necessary.

Jeff.

 

[shootin4par]

I follow you jeff. say we take what you are saying, and your right, and add an active arm push and pull, then we have all of the forces. have someone pull my car while I push it and it makes both our jobs easier. In your idea jeff, does the right arm add no power? or is it only the left arm blasting off the chest? PS, I edited it for you so it is more accurate in representing my point. thanks for pointing that out to me.

 

[JeffM]

Shootin4par

In the SLAP researcher's ModelPro model, the right side must keep up. That means that the central torque generator initiates and powers the golf swing, but the right side (right upper/lower arm) must keep up. A sign that the right arm is actively keeping up is the fact that the right arm approaches the torso and the right elbow approaches the right hip area extremely fast in the early downswing. One can see that in Mike Austin's swing. Finally, there is an additional right arm swing power source - the right forearm "twist and throw" maneuver that actively increases release of the right elbow joint after the golfer's hands reach the delivery position.

Jeff.

 

[shootin4par]

Jeff
the right elbow gets next to the right hip so fast because the increasing of the 2nd axis tilt puts it there whether or not you have a passive/active right arm
s4par

 

[JeffM]

I personally think that the right elbow actively moves to the right hip area soon after the downswing starts, and I don't think it has a causal connection with the degree of axis tilt.

See - http://perfectgolfswingreview.net/Faldo-BackView.jpg

Look how much the right elbow has moved down to the right hip area at the start of the downswing - even before significant axis tilt occurs.

Jeff.

 

[puttmad]

Jeff
The right elbow comes in towards the right side because the right side shortens making the right shoulder to drop causing axis tilt as per s4p's description...

 

[shootin4par]

I personally think that the right elbow actively moves to the right hip area soon after the downswing starts, and I don't think it has a causal connection with the degree of axis tilt.

See - http://perfectgolfswingreview.net/Faldo-BackView.jpg

Look how much the right elbow has moved down to the right hip area at the start of the downswing - even before significant axis tilt occurs.

Jeff.

his shoulders have rotated about 40*+, from the fitst pic to the second. that alone will momve the right elbow closer to his hip

 

[JeffM]

Puttmad

I agree that the right side shortens, and that brings the right elbow to the right side. However, there is no increased axis tilt at that stage of the downswing. Note the position of Faldo's head and spine in those two images.

Shootin4par

I agree that the shoulders rotate.

The rotation of the shoulders, and shortening of the right side, and movement of the right elbow to the right side ALL occur REACTIVELY/PASSIVELY in response to the initiating hip shift-rotation movement - and without any significant change in axis tilt. The majority of the secondary axis tilt that occurs in the downswing occurs in the later phase of the downswing when the lower body moves over to the left side while the head is kept back.

Jeff.

 

[shootin4par]

so the hips shift and this does not increase second axis tilt? So the pivot center is the c7 and the hips shift, base of spine. so with what you have written then the c7 must be moving forward while the hips shift, in order for no more second axis tilt to increase.

 

[mandrin]

mandrin, in your last two models the focus seems to be on the latteral motion of the hips and not so much on the rotational? In the 7th edition homer wanted the stoke pattern to be more of a shift from the top, or slide, and not so much rotational. yes it has to rotate back to square or very close to it but that is a lot less rotation then a tiger woods. what does your science say about homers slide rather then just trying to rotate your hips as far and as fast as you can? we know in kinetic energy that if the hips and shoulders are still rotating there has not been a full transfer of energy. so optimumly kinetic energy wise, they would be square at impact and allow the pendulum to not be comprimised. therefore maximizing the swing

shootin4par,

Rotation is represented by an angular velocity vector. Its magnitude represents the amplitude of the angular velocity and its direction in space is perpendicular to the plane in which the rotation takes place. More accurately in or parallel to this plane. This is illustrated in Fig1.

Fortunately, angular velocities can be added as vectors. This is not the case for angular accelerations. This means, for instance, that we can decompose a rotation into two or more independent rotations, or vice versa, can add them together.

A golfer mainly has two major axes of rotation, one through his spine or perhaps more vertical if he is a tripod-believer. The other one, a horizontal axis, to account for the rotation in the vertical plane. The latter being caused by the lateral weight shift.

Hence these two rotations can be represented by angular velocity vectors and, as mentioned above, can then be added to find the resulting angular vector and the associated swing plane. This is illustrated in Fig2.

The two rotational motions executed by a golfer hence define a composite plane. Coming back to your question. The lateral (rotational) slide you are referring to in your post can generate substantial kinetic energy, not to be ignored. Moreover as shown in Fig 2 it directly affects the steepness of the composite swing plane.

Thinking of the down swing as a composite action of rotation about two axes is quite instructive. You can think of simultaneous action; different weighting of each rotation; someone with little ‘lateral’ slide needs to ‘drop’ the arms to compensate; also view the downswing plane shift as being due to ending lateral rotational motion, see Fig3.

So far we have considered only two rotational motions of the body. There are also the arms and wrists which have to be considered to complete the picture. However one can have a downswing with very little independent arm motion (ala Dante).

 

[mandrin]

Mandrin:

I am curious about this statement:
"The work done by the central torque is acting on the club through both arm segments"

It seems confirmed by simply removing one of the arms that the ball cannot be struck as far.

But here's my question. You say that it's acting through both arm segments. What kind of torque is being created on the shoulders, and what role do they have in the direction of the force?

Ringer,

I will try to find some time, next week, to work out the mathematics for the forces/torques at the various joints due to external torques and checkrein constraint. However it would be useful if you could be more specific about the ‘force’ you refer to in your post.

 

[Jim Cook]

Question

Mandrin,
In figure 1 if I use the right hand rule and have my thumb pointing in the direction of the "angular velocity vector" the circular arrow around the "axis of rotation" and the arrow pointing from the head appears to be in the wrong direction or am I looking at it wrong?

Sorry to pick a few nits I always like your explainations.

 

[mandrin]

Mandrin,
In figure 1 if I use the right hand rule and have my thumb pointing in the direction of the "angular velocity vector" the circular arrow around the "axis of rotation" and the arrow pointing from the head appears to be in the wrong direction or am I looking at it wrong?

Sorry to pick a few nits I always like your explainations.

Jim,

Considering that I do everything myself, not the usual ‘copy/paste’ operation, considering the very limited time I take to produce quickly original material, I don’t think I am doing all that bad. But thanks for pointing it out, it is already corrected.

 

[Jim Cook]

Jim,

Considering that I do everything myself, not the usual ‘copy/paste’ operation, considering the very limited time I take to produce quickly original material, I don’t think I am doing all that bad. But thanks for pointing it out, it is already corrected.

Now I feel bad. I really like your explaination and seriously thought I was looking at it wrong. Please do not take my comments as negative. I look forward to more of your discussions.

 

[mandrin]

Now I feel bad. I really like your explaination and seriously thought I was looking at it wrong. Please do not take my comments as negative. I look forward to more of your discussions.

Jim, don’t feel bad, you are showing attention to fine details, excellent quality for a professional clubmaker.

 

[shootin4par]

mandrin,
I am trying real hard and I am sure in person you could explain it great. I appreciate your time and will read it more and try to figure more out of what you are saying cause you took the time to make the post in response to me. the terms throw me off. If I get some time this weekend I will define the terms and try to learn what you are saying exaclty.
thanks for the post
neil

 

[mandrin]

mandrin,
I am trying real hard and I am sure in person you could explain it great. I appreciate your time and will read it more and try to figure more out of what you are saying cause you took the time to make the post in response to me. the terms throw me off. If I get some time this weekend I will define the terms and try to learn what you are saying exaclty.
thanks for the post
neil

neil,

Science like TGM has its typical jargon. I will be away from my computer over the weekend, but will be happy thereafter to answer any questions you might want to throw at me.

 

[JeffM]

Shootin4par

You write-: "so the hips shift and this does not increase second axis tilt?"

Of course, the lateral hip shift towards the target increases axis tilt, but lateral hip shift occurs throughout most of the downswing, while the right elbow approaches the right hip in the early downswing - at which point insufficient lateral shift has occurred to produce a significant degree of axis tilt.

See - http://www.perfectgolfswingreview.net/AB-DS2-FO.jpg

Note that lateral hip shift has occurred and the right elbow is close to the right hip. Note the degree of axis tilt.

Then, see - http://www.perfectgolfswingreview.net/AB-ImpactPostimpactComposite-FO.jpg

Note that the degree of axis tilt has increased by impact, because the lower body has shifted even more to the left thereby moving the lower lumbar spine even more to the left while the head remains stationary.

The degree of axis tilt increases during the downswing - however, there is significantly more at impact compared to the early downswing.

Jeff.